No. 100 

1960 

SEVEN YEARS LATER: EFFECTS OF WILDFIRE 

IN A YOUNG STAND OF VIRGINIA PINE AND HARDWOODS 

In November 1952 a hot surface fire burned through 

part of a 30-year-old Virginia pine-hardwood stand near 

Beltsville, Md. Obseryations were made for the next 2 years 

to evaluate the effects of this type of fire under these 

stand conditions. The main direct effects during the 2 

years, as reported by Church in 1955 ', were: 45 percent 

mortality of trees 1 inch d.b.h. and larger, principally in 

the smaller size classes; and destruction of any pine seedlings that may have been present. An indirect effect, on 

the credit side, was the establishment of almost 11,000 pine 

seedlings per acre on the burn. During these 2 years, only 

250 pine seedlings per acre became established in an unburned portion of the same stand. 

Because of the strong surge of pine reproduction that 

came in on the burn, it seemed worth while to check developments in the stand after some further lapse of time. So, 

7 years after the fire and 5 years after Church's last tallies, we relocated and remeasured the four original plots. 

Three of the plots were in the burned area and one was just 

outside in part of the same original stand. 

Effects on Original Stand 

Superficially, there were no signs of a fire having 

occurred 7 years ago. But the measurements showed that the 

fire had caused rather significant continuing changes in the 

'Church, Thomas W., Jr. Observations follming wildfire in a young stand. of 

Virginia pine and hardwoods. U. S. Forest Serv. Northeast. Forest Expt. Sta. 

Forest Res. Note 49, 2 pp., 1955. 
Table 1.--Changes in basal area and numbers of living trees 

on burned and unburned areas before and after a wildfire 

in a Virginia pine-hardwood stand1 

'stems 0.6 inches and larger in d.b.h. 

St and 

condition 

Burned 

Unburned 

stand, as compared to areas outside the fire perimeter. 

Table 1 expresses these changes in terms of basal area and 

numbers of trees. There was a net loss of 20.4 square feet 

per acre in basal area on the burned plots during the 7-year 

period, although by 1959 the decline in numbers of living 

trees seemed to have ceased. This leveling-off was due in 

part to the ingrowth of hardwood sprouts. In st~iking contrast, there was a net gain of 43.1 square feet in basal 

area on the unburned area, even though the number of trees 

there has continued to decline. 

Although the number of trees 1 inch d.b.h. and larger 

has decreased in both stand conditions, the net decrease 

has been considerably greater on the burn. Much of the decrease has been in the smaller classes of pine. 

Basal area 

1952 1 1953 1 1954 1 1959 

Square feet per acre 

112.5 103.5 96.4 92.1 

127.1 125.4 -- 170.2 

Figure 1. --Stocking and survival of Virginia pine seedlings 

on the bun has been good, but the sparse foliage and 

general appearance indicate lack of vigorous growth because of continuing suppression. 

Living trees 

1952 1 1953 1 1954 1 1959 

Number per acre 

1,220 830 754 754 

1,180 1,100 1,020 860 
Figure 2. --This Virginia pine 

seedling--7 years old but 

scarcely 2 feet tall--is 

one of the larger seedlings 

on the burned area. The 

very limited growth can be 

attributed to continuing 

suppression, which has resulted in only one terminal 

growth period each year, 

rather than the usual two 

or three. 

Effects on Pine Regeneration 

Church advanced two principal reasons for the heavy 

restocking of Virginia pine seedlings on the burned plots: 

reduction in litter depth, particularly of the hardwood 

component; and decrease in shade by the killing of numerous 

small trees and some larger ones. 

These may well have been the main reasons responsible 

for the large influx of seedlings after this burn. But, to 

quote Church: "ultimate survival will depend upon competition from both the remaining overstory and the prolific 

hardwood sprouts." So far, the competition has not adversely 

affected the number of pine seedlings: there were 17,000 per 

acre present on the burn in 1959, as compared to some 11,000 

in 1954. 

Unfortunately, good stocking and survival are not 

necessarily correlated with vigorous growth. Most of the 

seedlings on the burn lack vigor, as indicated by their 

sparse foliage and meager height growth (fig. 1) And although some of the seedlings have probably been living at 

least since 1954, the largest are scarcely 2 feet tall and 

lack promising growth potential (fig. 2). Even if the overstory were now removed, it is unlikely that the suppressed 

seedlings would regain vigorous growth and good form. 

And what of the 250 seedlings per acre that were 

starting on the unburned plot in 19541 By 1959 they had 
disappeared, presumably because of suppression. The present 

large basal area of 170 square feet means bigger trees, a 

denser canopy, and less light getting through to the forest 

floor than in 1954. 

In Recapitulation 

These observations emphasize a frequently noted characteristic of Virginia pine--that the seedlings need full 

sunlight for good growth. Wildfires in Virginia pine or 

pine-hardwood stands usually kill back the smaller understory trees, often kill many overstory trees as well, and 

consume much of the litter, thereby opening the stands, decreasing competition, and providing seedbeds on which pines 

can start. 

But the beneficial effects for pine are only temporary if any substantial hardwood overstory or understory existed before the fire. Although many pine seedlings may 

start, they soon are overtopped and suppressed by resurging 

hardwood sprouts and the expanding crowns of surviving overstory trees. They cannot be expected to establish a pine 

stand without properly timed weeding and release treatments. 

--RICHARD H . FENTON 

Research Forester, Laurel Research Center 

Northeastern Forest Experiment Station 

Forest Service, U.S. Dept . Agriculture 

Laurel, Md.